There are two series of obstruent consonants. Both usually produce a noticeable delay before the onset of the next vowel: the series 'fortis' (written p t č k kw s h hw) tends to be aspirated, with a noisy transition to the vowel, while the series 'lenis' (written b d g gw 'z), optionally voiced, is glottalized, with a silent transition to the vowel, which in turn tends to be laryngealized. The glottal stop is weak and is noted mainly for the laryngeal effect it has on adjacent vowels.